Method To Control Corrosion Of A Metal Surface Using Alkyl Sulfamic Acids Or Salts Thereof

ABSTRACT

The present invention provides a method of inhibiting corrosion of a metal surface with at least one alkyl sulfamic acid or salt thereof to the metal surface in an amount effective to inhibit corrosion of the metal surface. The alkyl sulfamic acid or salt thereof can be applied in any suitable manner to the metal surface, for example, flowing, coating, sponging, wiping, spraying, painting, showering, and/or misting.

This application claims the benefit under 35 U.S.C. §119(e) of priorU.S. Provisional Patent Application No. 61/783,706, filed Mar. 14, 2013,which is incorporated in its entirety by reference herein.

BACKGROUND OF THE INVENTION

The present invention relates to the inhibition of corrosion of a metalsurface using one or more anti-corrosion agents.

Corrosion has been the subject of scientific study for more than 150years. Corrosion is a naturally occurring phenomenon that relates to thedeterioration of a material or its properties because of a reaction withits environment. In addition to reduced longevity, corrosion alsoproduces oxides that can further deteriorate a system by erosion,plugging, and fouling. Oxides can deposit on heat transfer surfaces,reducing efficiency, and increasing energy costs. Common sources ofcorrosion include dissolved oxygen, bacteria, electrolysis (straycurrent), differential metal (dielectric), and differential cells. Flow,temperature, and pressure can effect the corrosion rate.

Corrosion inhibitors are used in oil and gas exploration and production,petroleum refining, chemical manufacturing, heavy manufacturing, watertreatment, and the product additive industries. As products andmanufacturing processes have become more complex and the consequences ofcorrosion more costly, greater attention is being given to the controland prevention of corrosion. Thus, there is a continued need to identifymore effective corrosion inhibitors that minimize financial andenvironmental costs with better toxicological profiles.

SUMMARY OF THE INVENTION

A feature of the present invention is to inhibit corrosion of a metalsurface.

Another feature of this invention is to provide methods of using ananti-corrosion agent having low toxicity and/or high efficacy to preventor minimize the corrosion of metal surfaces.

Methods of inhibiting the corrosion of metal surfaces located in avariety of different systems and environments are also features of thisinvention.

To achieve these and other advantages and in accordance with thepurposes of the present invention, as embodied and broadly describedherein, the present invention provides a method of inhibiting corrosionof a metal surface including applying at least one alkyl sulfamic acidor salt thereof to the metal surface in an amount effective to inhibitcorrosion of the metal surface. At least one alkyl sulfamic acid or saltthereof can be applied in any suitable manner to the metal surface, forexample, the application can include one or more of the following:flowing, coating, sponging, wiping, spraying, painting, showering, andmisting. The method can further include subjecting the treated metalsurface with corrosive agent(s).

Additional features and advantages of the present invention will be setforth in part in the description which follows, and in part will beapparent from the description, or may be learned by practice of thepresent invention. The objectives and other advantages of the presentinvention will be realized and obtained by means of the elements andcombinations particularly pointed out in the written description andappended claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are only intended to provide a further explanation of the presentinvention, as claimed.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The present invention provides a method of inhibiting corrosion of ametal surface including applying at least one alkyl sulfamic acid orsalt thereof or a solution containing the alkyl sulfamic acid or salt,to the metal surface in an amount effective to inhibit corrosion of themetal surface. Any type of corrosion can be inhibited as characterizedby cause and/or effect. For example, the corrosion can include uniformcorrosion that extends evenly across the surface, pitting corrosion thatis uneven and has smaller deep areas (pits), exfoliation corrosion thatmoves along layers of elongated grains, and/or intergranular corrosionthat grows along grain boundaries.

Any suitable or desirable alkylated derivative of sulfamic acid, saltthereof, combinations thereof can be used in the present invention. Morethan one alkylated derivative of sulfamic acid or salt thereof can beused. Sulfamic acid is also known as amidosulfonic acid, amidosulfuricacid, aminosulfonic acid, and sulfamidic acid. Sulfamic acid is amolecular compound having the formula H₃NSO₃. Sulfamates can beO-substituted, N-substituted-, or di-/tri-substituted derivatives ofsulfamic acid and are also considered to be sulfamic acids or saltsthereof for purposes of the present invention. Both tautomers H₃NSO₃ andH₂NSO₂(OH) fall within the scope of sulfamic acids or salts thereof inthe present invention. Alkylated derivatives of these sulfamic acids canbe used.

The alkylated derivative of sulfamic acid can thus be an alkyl sulfamicacid or salt thereof. The alkyl group can contain any desirable numberof carbons in a linear, branched, and/or cyclic configuration. Forexample, the alkyl group can be methyl, ethyl, propyl, butyl, pentyl,hexyl, heptyl, octyl, nonyl, decyl, dodecyl, isopropyl, isobutyl,sec-butyl, tert-butyl, neopentyl, and the like. The at least onesulfamic acid can have the formula R₁R₂NS(O)₂(OH), and, for example, R₁and R₂ are independently a hydrogen, a C₄-C₂₀ alkyl group, or acycloalkyl group, and R₁ and R₂ are not both hydrogen, and/or R₁, R₂,and the N form a 5-8 membered heterocyclic ring including one or more ofO, NH, and CH₂. The at least one alkyl sulfamic acid can have theformula R₁R₂NS(O)₂(OH) and, for example, R₁ and R₂ can independently bea hydrogen, a C₄-C₂₀ alkyl group, or a cycloalkyl group, and R₁ and R₂are not both hydrogen. The at least one alkyl sulfamic acid can have theformula R₁R₂NS(O)₂(OH), and, for example, R₁ or R₂, but not both, is aC₄-C₂₀ alkyl group or a cycloalkyl group. The at least one alkylsulfamic acid can have the formula R₁R₂NS(O)₂(OH) and, for example, bothR₁ and R₂ are a C₄-C₂₀ alkyl group or cycloalkyl group. The at least onealkyl sulfamic acid can have the formula R₁R₂NS(O)₂(OH) and, forexample, R₁, R₂, and the N form a 5-8 membered heterocyclic ringincluding one or more of O, NH, and CH₂. The sulfamic acid or saltthereof can be a halide derivative of a sulfamic acid. Examples ofsulfamic acids and salts thereof that can be alkylated (if not soalready) employed in the method of the present invention include thosedescribed in U.S. Pat. Nos. 7,576,041; 7,470,652; 7,345,202; 6,983,614;6,824,668; 6,380,182; 6,110,387; 6,103,131; 5,478,461; 5,431,839;4,386,060; 4,327,034; 4,049,709; 3,223,704; and 3,536,759, which areincorporated herein by reference in their entireties. Salts include, butare not limited to, alkali metal and quaternary ammonium salts. Methodsfor the preparation of various sulfamic acids or salts thereof aredescribed in Nickless, Inorganic Sulphur Chemistry, Elsevier PublishingCompany, New York; 611-614 (1968), which is incorporated by reference inits entirety.

The alkyl sulfamic acid or salt thereof can be applied by itself to ametal surface or applied as part of a fluid that can optionally containone or more additional components, for example, an additionalanti-corrosion agent and/or a biocide. When combined with one or moreadditional anti-corrosion agents, the resulting corrosion inhibition canbe sub-additive, additive, or super-additive (synergistic). The fluidcan include a liquid, a vapor (gas), or a combination thereof. The fluidcan include H₂O, NH₃, and/or an alcohol. The fluid can be aqueous,non-aqueous, or both. The fluid can include an acid or base in additionto the alkyl sulfamic acid or salt thereof. The fluid can include a saltsolution of at least one salt independent of an alkyl sulfamic acidsalt.

The fluid containing the alkyl sulfamic acid or salt thereof can becooled or heated, or be used at ambient temperature or othertemperatures above or below 20 deg C. The pH of the fluid can be neutralor from about 0.0 to about 14, from about 2.0 to about 12, from about4.0 to about 10, or from about 6.0 to about 8.0.

The concentration of the at least one alkyl sulfamic acid or saltthereof can be adjusted according to the particular metal surface(s)being treated and the parameters of the system in which it is employed.The concentration of at least one alkyl sulfamic acid or salt thereof ina fluid system can be less than 0.001 ppm, greater than 0.001 ppm, fromabout 0.001 ppm to about 10,000 ppm from about 0.01 to about 1,000 ppm,from about 0.1 ppm to about 100 ppm, or from about 1.0 ppm to about 50ppm, or from about 0.5 ppm to about 25 ppm, or from about 1 ppm to about15 ppm, or from about 1 ppm to about 10 ppm, or from about 1 ppm toabout 5 ppm. The alkyl sulfamic acid or salt thereof can be prepared asa stock solution of from about 0.01 wt % to about 100 wt %, from about0.1 wt % to about 95 wt %, from about 1.0 wt % to about 80 wt %, fromabout 5.0 wt % to about 75 wt %, from about 10 wt % to about 60 wt %,from about 15 wt % to about 50 wt % from about 25 wt % to about 40 wt %alkyl sulfamic acid or salt thereof based on the total weight of thestock solution. The alkyl sulfamic acid or salt thereof can be used inthe methods of the invention as a solid, liquid, and/or gaseousformulation. The methods according to the invention can be part of anoverall water treatment regimen. The alkyl sulfamic acid or salt thereofcan be used with other water treatment chemicals, such as biocides(e.g., algicides, fungicides, bactericides, molluscicides, oxidizers,etc.), stain removers, clarifiers, flocculants, coagulants, or otherchemicals commonly used in water treatment.

Depending on its use, a composition containing alkyl sulfamic acid orsalt thereof according to the present invention can be prepared invarious forms known in the art. For example, the composition can beprepared in liquid form as a solution, dispersion, emulsion, suspension,or paste; a dispersion, suspension, or paste in a non-solvent; or as asolution by dissolving the alkyl sulfamic acid or salt thereof in asolvent or combination of solvents. Suitable solvents include, but arenot limited to, acetone, glycols, alcohols, ethers, water, or otherwater-dispersible solvents. The composition can be prepared as a liquidconcentrate for dilution prior to its intended use. Common additivessuch as surfactants, emulsifiers, dispersants, and the like can be usedas known in the art to increase the solubility of the alkyl sulfamicacid or its salt as well as other components in a liquid composition orsystem, such as an aqueous composition or system. The composition of theinvention can be solubilized by simple agitation.

A composition of the present invention can be prepared in solid form.For example, the alkyl sulfamic acid or salt thereof can be formulatedas a powder or tablet using means known in the art. The tablets cancontain a variety of excipients known in the tableting art such as dyesor other coloring agents. Other components known in the art such asfillers, binders, glidants, lubricants, or antiadherents can beincluded. These components can be included to improve tablet propertiesand/or the tableting process.

The alkyl sulfamic acid, salt thereof, and/or composition including thesame can be applied directly or indirectly to a metal surface using anyappropriate technique, for example flowing, coating, sponging, wiping,spraying, painting, showering, and/or misting of the at least one alkylsulfamic acid or salt thereof to the metal surface can be employed. The“applying” can include flowing a fluid containing the at least one alkylsulfamic acid or salt thereof over the metal surface. The method cancomprise forming a protective film on the metal surface including the atleast one alkyl sulfamic acid or salt thereof.

The corrosion of any suitable metal surface can be inhibited using themethods of the invention. Any metal, combination of metals, or alloyscan be protected. Even surfaces that contain minor amounts or traceamounts of one or metals can be protected. The metal can be any metalsusceptible to corrosion including industrial metals. Examples of metalsurfaces include those containing one or more of scandium, titanium,vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc,yttrium, zirconium, platinum, gold, mercury, niobium, iridium,molybdenum, technetium, ruthenium, rhodium, palladium, silver, cadmium,hafnium, tantalum, tungsten, rhenium, osmium, aluminum, indium,germanium, gallium, antimony, tin, lead, bismuth, cerium, praseodymium,neodymium, promethium, samarium, europium, gadolinium, terbium,dysprosium, holmium, erbium, thulium, and/or ytterbium and/or alloys ofone or more of these metals. Alloy metals such as stainless steel,steel, mild steel, bronze, brass, and the like are further examples ofmetals. The metal surface can be a ferrous or a non-ferrous surface. Thesurface can have any shape and/or dimensions. The metal surface can becontinuous or discontinuous. The metal can be embedded in one or morenon-metal media such as a plastic, a rubber, a glass, a ceramic, acomposite, or the like. The metal can be electroplated. The metal can begalvanized. A constant or variable electric current and/or magneticfield can be applied to the metal surface. The metal surface can beheated or cooled.

The method of the invention can further include contacting the metalsurface with at least one corrosive agent from which protection issought. The applying of the alkyl sulfamic acid, salt thereof, and/orone or more other anti-corrosive agents can be performed before, during,and/or after the contacting of the metal surface with the at least onecorrosive agent. The metal surface can be part of a closed fluid systemor an open fluid system, or both. Examples of systems that can betreated include, but are not limited to cooling systems, heatingsystems, cooling towers, boilers, radiators, steam piping, oil transportmachinery and piping, oil production machinery and piping, paper andpulp machinery, drinking and tap water treatment plants, plumbing,sewers, waste water treatment plants, and other industrial uses thatcome in contact with corrosive agents.

An amount effective to inhibit corrosion is an amount that results in alower degree of chemical change of the metal surface in the presence ofan anti-corrosion inhibitor than in its absence. Corrosion inhibitioncan be partial inhibition or complete inhibition. The chemical changecan be measured, for example, by measuring a change in weight of themetal surface and/or by measuring the concentration of metal, ionsthereof, or salts thereof originating from the metal surface in fluidthat flows past the metal surface. The weight loss, for example, of acorrosion coupon after exposure to a corrosive environment can beexpressed as mils (thousandths of an inch) per year penetration (MPY).The corrosion rate can be calculated with the assumption of uniformcorrosion over the entire surface of the coupon. MPY can be calculatedby multiplying the weight loss in grams by 22,300 and then dividing bythe product of the area of coupon (sq. in.), the metal density of thecoupon (g/cm³), and the time of exposure in a corrosive environment(days). 1 MPY is equal to 0.0254 mm/y, which is equal to 25.4 μm/y.Accordingly, corrosion rate from metal loss can be calculated asmm/y=87.6×(W/DAT) with W (weight loss in milligrams), D (metal densityin g/cm³), A (area of sample in cm²), and T (time of exposure of themetal sample in hours).

Metal corrosion can occur via electrochemical reactions at the interfacebetween a metal and an electrolyte solution. A thin film of moisture ona metal surface forms the electrolyte for atmospheric corrosion.Corrosion normally occurs at a rate determined by an equilibrium betweenopposing electrochemical reactions, anodic (metal oxidation) andcathodic (reduction of a solution species). These reactions can occur onone metal or on two or more dissimilar metals that are in electricalcommunication. Corrosion current can be used to generate a corrosionrate by assuming an electrolytic dissolution reaction involving achemical species. Uniform corrosion across a metal surface allowscalculation of the corrosion rate in units of distance per year. For analloy undergoing uniform dissolution, equivalent weight is a weightedaverage of the equivalent weights of the alloy components. If thedissolution is not uniform, corrosion products can be used to calculateequivalent weight.

A weight loss can be converted to a corrosion rate with knowledge of thedensity and the sample area of a sample. ASTM Standard G 102, StandardPractice for Calculation of Corrosion Rates and Related Information fromElectrochemical Measurements can be used. An eddy current instrument andprobe can be used for measuring corrosion by monitoring a conductivitycurve and impedance plane and using one or more techniques such assingle layer corrosion detection, two layer corrosion detection, alimited penetration method, dual frequency method, and/or a variablefrequency method.

The following examples are intended to illustrate, not limit, thepresent invention.

EXAMPLES Example 1

Copper metal sample coupons with a surface area of 3.38 in² wereinstalled in a laboratory-scale liquid recirculating loop equipped witha reservoir capable of holding approximately 11 L total volume. Theapparatus was designed to hold metal sample coupons in the path offlowing liquid at a chosen flow rate and temperature for chosen periodof time. After exposure for an adequate period of time, the metal sampleweight loss resulting from corrosion was used to calculate the corrosionrate. The exact conditions of the tests are listed in the Tables 1-3.For tests shown in all three tables, the temperature was 35° C., linearvelocity was 7 gallons per minute (GPM) (3 ft/s), and the mass oftreatment was 10 L. Synthetic water was used having 1170 ppm NaCl and505 ppm NaHCO₃, at pH 8.

For the purpose of evaluating yellow-metal corrosion inhibitorperformance, corrosion rate data was generated for the trial material(hexylsulfamic acid) and a known industry corrosion inhibitor(tolyltriazole) (identified as “TTA” in the Tables) as a control, and insome cases untreated (blank) systems, using copper test coupons insodium chloride-sodium bicarbonate brine at initial pH 8.8. This aqueousmatrix was designed to mimic the pH, alkalinity, and total dissolvedsolids that might be found in a secondary treated municipal wastewaterafter four cycles of concentration. The inhibitor dosage range of from 5ppm to 10 ppm was selected because this is an effective dosage range forthe protection of copper with tolytriazole.

After exposure to the corrosive environment defined by the testingparameters, corrosion coupons were cleaned with an acidic solution thatis capable of removing various chemical and biological deposits andfilms that might have formed on the coupon surface during exposure tothe test environment. The weight change (and corresponding corrosionrate) determined before a coupon has been chemically cleaned helps theresearcher ascertain general material removal and/or deposition processinformation. The corrosion rate obtained after cleaning is consideredthe true corrosion rate for the system under evaluation. Comparativedata from known corrosion inhibitors and/or untreated systems collectedat the time of the subject inhibitor evaluation are advantageous due tovariability in experimental factors that otherwise are not easilycontrolled between different experiments. In the tables, the MPY(milli-inch per year) of corrosion was determined.

The data presented in Tables 1-3 show that hexylsulfamic acid hascorrosion inhibitor properties that result in copper corrosion rates farless than that obtained in untreated systems. The data also show thatthe copper corrosion inhibition performance of hexylsulfamic acid issimilar to that obtained for tolyltriazole. The data also show thathexylsulfamic acid performance as a copper corrosion inhibitor has aninverse relationship with inhibitor concentration under the given testconditions, which is similar to the performance trend obtained withtolyltriazole. Put another way, lower dosages, treatment levels, weremore effective in controlling corrosion than higher dosages.

TABLE 1 Inhib- Weight itor Loss/ Dosage Gain Area Time Treatment Couponppm pH grams MPY in² hours 5 ppm Copper, 5 8.8 0.0009 0.025 3.38 649active TTA CDA110 (before cleaning) 5 ppm Copper, 5 8.8 0.0043 0.1183.38 649 active TTA CDA110 (after cleaning) 5 ppm Hexyl Copper, 5 8.80.0009 0.025 3.38 649 Sulfamic Acid CDA110 (before cleaning) 5 ppm HexylCopper, 5 8.8 0.0043 0.118 3.38 649 Sulfamic Acid CDA110 (aftercleaning) 10 ppm Hexyl Copper, 10 8.8 0.0068 0.186 3.38 649 SulfamicAcid CDA110 (after cleaning) 10 ppm Hexyl Copper, 10 8.8 0.0214 0.5863.38 649 Sulfamic Acid CDA110 (after cleaning)

TABLE 2 Inhib- Weight itor Loss/ Dosage Gain Area Time Treatment Couponppm pH grams MPY in² hours Blank (before Copper, 0 8.8 0.0086 0.097 3.381575 cleaning) CDA110 Blank (after Copper, 0 8.8 0.0188 0.212 3.38 1575cleaning) CDA110 5 ppm Copper, 5 8.8 0.0022 0.025 3.38 1575 active TTACDA110 (before cleaning) 5 ppm Copper, 5 8.8 0.0056 0.063 3.38 1575active TTA CDA110 (after cleaning) 10 ppm Hexyl Copper, 10 8.8 0.00440.050 3.38 1575 Sulfamic Acid CDA110 (before cleaning) 10 ppm HexylCopper, 10 8.8 0.0111 0.125 3.38 1575 Sulfamic Acid CDA110 (aftercleaning)

TABLE 3 Inhib- Weight itor Loss/ Dosage Gain Area Time Treatment Couponppm pH grams MPY in² hours 5 ppm Hexyl Copper, 5 8.8 0.0018 0.174 3.38184 Sulfamic Acid CDA110 (before cleaning) 5 ppm Hexyl Copper, 5 8.80.0055 0.531 3.38 184 Sulfamic Acid CDA110 (after cleaning) 7.5 ppmHexyl Copper, 7.5 8.8 0.0036 0.348 3.38 184 Sulfamic Acid CDA110 (beforecleaning) 7.5 ppm Hexyl Copper, 7.5 8.8 0.0089 0.860 3.38 184 SulfamicAcid CDA110 (after cleaning) 10 ppm Hexyl Copper, 10 8.8 0.0033 0.3193.38 184 Sulfamic Acid CDA110 (before cleaning) 10 ppm Hexyl Copper, 108.8 0.0097 0.937 3.38 184 Sulfamic Acid CDA110 (after cleaning)

The present invention includes the followingaspects/embodiments/features in any order and/or in any combination:

1. A method of inhibiting corrosion of a metal surface comprising:applying at least one alkyl sulfamic acid or salt thereof to the metalsurface in an amount effective to inhibit corrosion of the metalsurface.2. The method of any preceding or following embodiment/feature/aspect,wherein said alkyl sulfamic acid is a C₁-C₁₂ alkyl sulfamic acid or saltthereof.3. The method of any preceding or following embodiment/feature/aspect,wherein the at least one alkyl sulfamic acid has the formulaR₁R₂NS(O)₂(OH), and

R₁ and R₂ are independently a hydrogen, a C₄-C₂₀ alkyl group, or acycloalkyl group, and R₁ and R₂ are not both hydrogen, and/or

R₁, R₂, and the N form a 5-8 membered heterocyclic ring including one ormore of O, NH, and CH₂.

4. The method of any preceding or following embodiment/feature/aspect,wherein R₁ and R₂ are independently a hydrogen, a C₄-C₂₀ alkyl group, ora cycloalkyl group, and R₁ and R₂ are not both hydrogen.5. The method of any preceding or following embodiment/feature/aspect,wherein R₁ or R₂, but not both, is a C₄-C₂₀ alkyl group or a cycloalkylgroup.6. The method of any preceding or following embodiment/feature/aspect,wherein both R₁ and R₂ are a C₄-C₂₀ alkyl group or cycloalkyl group.7. The method of any preceding or following embodiment/feature/aspect,wherein R₁, R₂, and the N form a 5-8 membered heterocyclic ringincluding one or more of O, NH, and CH₂.8. The method of any preceding or following embodiment/feature/aspect,wherein the alkyl sulfamic acid or salt thereof is present in a fluidapplied to the metal surface.9. The method of any preceding or following embodiment/feature/aspect,wherein the fluid is a liquid.10. The method of any preceding or following embodiment/feature/aspect,wherein the fluid is a vapor.11. The method of any preceding or following embodiment/feature/aspect,wherein the fluid comprises at least one of H₂O, NH₃, and an alcohol.12. The method of any preceding or following embodiment/feature/aspect,wherein the fluid comprises an acid or base in addition to the alkylsulfamic acid or salt thereof.13. The method of any preceding or following embodiment/feature/aspect,wherein the fluid comprises a salt solution of at least one saltindependent of the alkyl sulfamic acid salt.14. The method of any preceding or following embodiment/feature/aspect,wherein the applying comprises one or more of flowing, coating,sponging, wiping, spraying, painting, showering, and misting of the atleast one alkyl sulfamic acid or salt thereof.15. The method of any preceding or following embodiment/feature/aspect,wherein the applying comprises flowing a fluid comprising the at leastone alkyl sulfamic acid or salt thereof over the metal surface.16. The method of any preceding or following embodiment/feature/aspect,wherein the metal surface is a non-ferrous surface.17. The method of any preceding or following embodiment/feature/aspect,wherein the metal surface comprises copper or a copper-containing alloy(e.g., bronze).18. The method of any preceding or following embodiment/feature/aspect,further comprising contacting the metal surface with at least onecorrosive agent.19. The method of any preceding or following embodiment/feature/aspect,wherein the applying is performed before, during, and/or after thecontacting.20. The method of any preceding or following embodiment/feature/aspect,wherein the metal surface is part of a closed fluid system.

The present invention can include any combination of these variousaspects, features, or embodiments above and/or below as set forth insentences and/or paragraphs. Any combination of disclosed featuresherein is considered part of the present invention and no limitation isintended with respect to combinable features.

Applicants specifically incorporate the entire contents of all citedreferences in this disclosure. Further, when an amount, concentration,or other value or parameter is given as either a range, preferred range,or a list of upper preferable values and lower preferable values, thisis to be understood as specifically disclosing all ranges formed fromany pair of any upper range limit or preferred value and any lower rangelimit or preferred value, regardless of whether ranges are separatelydisclosed. Where a range of numerical values is recited herein, unlessotherwise stated, the range is intended to include the endpointsthereof, and all integers and fractions within the range. It is notintended that the scope of the invention be limited to the specificvalues recited when defining a range.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the embodiments of thepresent invention without departing from the spirit or scope of thepresent invention. Thus, it is intended that the present inventioncovers other modifications and variations of this invention providedthey come within the scope of the appended claims and their equivalents.

What is claimed is:
 1. A method of inhibiting corrosion of a metalsurface comprising: applying at least one alkyl sulfamic acid or saltthereof to the metal surface in an amount effective to inhibit corrosionof the metal surface.
 2. The method of claim 1, wherein said alkylsulfamic acid is a C₁-C₁₂ alkyl sulfamic acid or salt thereof.
 3. Themethod of claim 1, wherein the at least one alkyl sulfamic acid has theformula R₁R₂NS(O)₂(OH), and R₁ and R₂ are independently a hydrogen, aC₄-C₂₀ alkyl group, or a cycloalkyl group, and R1 and R2 are not bothhydrogen, and/or R₁, R₂, and the N form a 5-8 membered heterocyclic ringincluding one or more of O, NH, and CH₂.
 4. The method of claim 1,wherein R₁ and R₂ are independently a hydrogen, a C₄-C₂₀ alkyl group, ora cycloalkyl group, and R₁ and R₂ are not both hydrogen.
 5. The methodof claim 1, wherein R₁ or R₂, but not both, is a C4-C₂₀ alkyl group or acycloalkyl group.
 6. The method of claim 1, wherein both R₁ and R₂ are aC₄-C₂₀ alkyl group or cycloalkyl group.
 7. The method of claim 1,wherein R₁, R₂, and the N form a 5-8 membered heterocyclic ringincluding one or more of O, NH, and CH₂.
 8. The method of claim 1,wherein the alkyl sulfamic acid or salt thereof is present in a fluidapplied to the metal surface.
 9. The method of claim 8, wherein thefluid is a liquid.
 10. The method of claim 8, wherein the fluid is avapor.
 11. The method of claim 8, wherein the fluid comprises at leastone of H₂O, NH₃, and an alcohol.
 12. The method of claim 8, wherein thefluid comprises an acid or base in addition to the alkyl sulfamic acidor salt thereof.
 13. The method of claim 8, wherein the fluid comprisesa salt solution of at least one salt independent of a alkyl sulfamicacid salt.
 14. The method of claim 1, wherein the applying comprises oneor more of flowing, coating, sponging, wiping, spraying, painting,showering, and misting of the at least one alkyl sulfamic acid or saltthereof.
 15. The method of claim 1, wherein the applying comprisesflowing a fluid comprising the at least one alkyl sulfamic acid or saltthereof over the metal surface.
 16. The method of claim 1, wherein themetal surface is a non-ferrous surface.
 17. The method of claim 1,wherein the metal surface comprises copper or a copper-containing alloy.18. The method of claim 1, further comprising contacting the metalsurface with at least one corrosive agent.
 19. The method of claim 16,wherein the applying is performed before, during, and/or after thecontacting.
 20. The method of claim 1, wherein the metal surface is partof a closed fluid system.